Recovery of lubricating oil from acid sludge



April 23, 1940. J. B. sYNNoT-r, JR

RECOVERY OF LUBRICATING OIL FROM ACID SLUDGE Filed May lO, 1958 IIB J. BRUCE SYNNoTTl JR.

INVENTOR ATTORN EYS Patented pr'. 23, 1940 UNITED STATES RECOVERY OF LUBRICATING OIL FROM ACID SLUDGE Judson Bruce Synnott, Jr., Port Arthur, Tex., as-

signor to The Texas Company, New York, N. Y., v a corporation of Delaware y Application May l0, 1938, Serial No. 207,001 v 6 Claims.

This invention relates to the recovery of lubricating oil from acid sludge derived from the treatment of petroleum lubricating oil with sulfuric acid.

The process of the invention is particularly useful in the recovery of lubricating oil from acid sludge derived from the treatment of residual lubricating oils. In the treatment of residual lubricating oils with sulfuric acid from 25% to 50% of the oil is ordinarily lost as acid sludge.

' The process of the invention is also useful in the recovery of lubricating oil from acid sludge obtained in the treatment of distillate lubricating oils. In the treatment of distillate lubricating oils with sulfuric acid from 5% to 15% of the oil is usually lost as acid sludge.

In the past efforts to recover acid sludge have been directed more particularly to the recovery of acid from the sludge. Veryl little attention has been given to the recovery of lubricating oil from acid sludge. It is common practice to dispose of acid sludge, after separation of a part of the contained acid, as a waste product.

I have discovered that a large part of the acid sludge which is produced in the treatment of petroleum lubricating oil with sulfuric acid consists of valuable lubricatingoil which can be recovered. It is an object of the'invention to provide a practical method for recovering said valuable lubricating oil.

My invention concerns a method of recovering lubricating oil from acid sludge derived from the treatment of petroleum lubricating oil with sulfurie acid. According to the invention low boiling petroleum oil and water are added to the acid sludge and the following materials are separated from the sludge: Y

1. An acid oil consisting oa portion of the sludge dissolved in the low boiling petroleum oil.

2. An asphaltic material which is relatively insoluble in the low boiling petroleum oil.

3. Weak acid.

The acid oil above described is neutralized by heating it to decompose and vaporize contained acid compounds and the acid vapors are separated from the oil. The neutralized oil is distilled and the low boiling petroleum oil is separated therefrom. Lubricating oil is recovered from the oil remaining after the separation of the low boiling petroleum oil.

The invention will be more fully understood by referring to the following description and the accompanying drawing.

The single figure of the drawing is a diagrammatic view in elevation of apparatus suitable for (C1. isfiis) recovering lubricating oil from acid sludge in accordance with the process of the invention.

In carrying out the process of the invention, a lubricating oil, which may be. a distillate oilk or a residual oil obtained from any type oi crude 5 oil, may be treated with sulfuric acid and the treated oil may be separated from the acid sludge. If desired the acid sludge derived from theacid treatment of different types of lubricating Voils `may be segregated according to the type of oil 10 treated, but for convenience and economy the acid sludge produced in the acid treatment of a plurality of lubricating oil stocks maybe commingled and recovered in a single operation. It is contemplated that in most oil refining plants ay composite lubricating oil sludge can be made available which Will be of substantially uniform quality over a long periodof time. The process of the invention can be carried out to best advantage as a continuousprocess. The first step of the process comprises addin low boiling petroleum oil and water to the acid sludge and separating from the sludge an acid oil consisting of a portion of the sludge dissolved in the low boiling petroleum oil, an asphaltic material which is relatively insoluble in the low boiling petroleum oil, and weak acid. The low boiling petroleum oil may consist of a light gas oil, for example. A cycle gas oil of the type which f is ordinarily obtained as aby-product of a crack- '30 ing operation, in the manufacture of gasoline from oils of higher boiling point, and which, because of its refractory nature, is not economical to use as a cracking stock, is particularly suitable for use in the process of this invention. v

The separation of the acid sludge which has been described in the preceding paragraph may be accomplished in stages if desired. The following example illustrates a method which may be l employed in effecting this separation: "40

Referring to the drawing, the acid sludge may be mixed with from about 10% to about 15% of water and from about '75% to about 95% of 'low boiling petroleum oil, for example, and delivered to a vessel l through a pipe 2. In the vessel I the mixture may be heated in direct contact with steam introduced through a pipe 3 for about 5 hours, for example. The vessel l preferably is a closedvessel, soI that the sludge mixture maybe heated therein out of contact with' air. A pres- 50 sure ranging from atmospheric pressure to a pressure of about 100 pounds per square inch, for example, may be maintained on the'mixture while it is being heated. Immediately following the heating step the sludge mixture may be allowed to settle for about 5 hours, for example. The settling step also may be carried out in the vessel I.

An inert gas such as flue gas may be introduced into the vessel I during the settling step through a pipe li to provide a blanket which will protect` the sludge mixture from contact with air. Upon settling the sludge mixture an acid oil consistingora portion of the sludge dissolved 'in low boiling petroleum oil may be separated from the remainder of the sludge mixture. Said acid oil may be withdrawn from the vessel I thru draw-off pipes 5, 6 and l and; delivered into a may be repeated one or more times and `addi- Utional amounts of 4acid oil and weak acid may bey separated from the sludge. Finally an as- "phaltic material maybe recovered which is relatively insoluble in the low boiling petroleum oil. `4Preferably the heating and settling steps above described Afare carried out in vessels which are lined with a corrosion resistant material.

The

' gases produced. during the process should be be provided in the tower i3.

thru a pipe i6.

rtreated to remove objectionable compounds therefrom before discharging them to the atmospher'e.

The acid oil may be withdrawn from the tank .8 thrua pipe l0, by means of a pump Il. A

. 35.k vided for closing the pipe l0 in the event of an valve i2, which is situated in the pipe I0, is proernergency. The pipe I0 discharges into the up- Mper portion'of a fractionating tower I3.y The fractionating tower i3 preferably is lined with an acid resistant material such as acid brick. The acid resistant lining is indicated by the numeral I3.' Contacting devices such as the bafes l 5 may The acid oil is passed downwardly in the tower I3 and is heated by direct Contact with hot vapors which are introduced into the lower portion of the tower I3 The hot vapors are produced by heating a low boiling petroleum oil of the type above described, as will be explained more fully inthe following remarks. Theacid oil is thus heated to a temperature suiiiciently high to decompose and vaporize contained acid compounds. Preferably a temperature of from about 400 F. to about 550 F. isv maintainedr in the tower I3.

' The vaporized acid compounds may be separated from the acid oil and withdrawn from the tower I 3 thru a pipe l?. The acid vapors may be condensed by means of a jet condenser I9.

Water may be delivered to the jet condenser i9 thru a pipe 20. A valve ZI, which is situated in the pipe 20, regulates the amount of water which is delivered to the jet condenser I9. A neutralizing agent such sodium hydroxide may be introduced into the pipe 23 thru a pipe 22. A valve 23,k which is situated inthe pipe 22, regulates the amount of neutralizingagent which is delivered into the pipe 2t.

The mixture of condensed acid vapors and wa- 'ter leaving the jet condenser I9 may beV delivered into a water separator llthru a pipe 25. Water is withdrawn from the water separator Z thru a pipe 2. vA valve 23, which is situated in the pipe 2l, is provided for disconnecting the Awater Uncondensed gases may be withdrawn from the lwater `sepa.-

rator 24 thru a pipe 29. "hese gases should be treated to remove objectionable compounds therefrom before discharging them to the atmosphere.

The neutralized oil from which the acid vapors have been separated may be withdrawn from the tower I3 thru a pipe 3l. The hot vapors which are delivered into the tower I3 thru the pipe I6 may be condensed by contact with the relatively i cold oil which is introduced to the tower I3 thru l0 the pipe l0. The low boiling petroleum oil produced by .condensation of said vapors may be Vwithdrawn from the tower I3 along with said neutralized oil.

-The neutralized oil withdrawn from the tower I3 maybe delivered to a heating coil 33 by means of a pump 34 which is situated in the pipe 3l. The heating coil 33 is situated in a furnace 35. A burner 36 is provided for supplying heat to the heating coil 33. 'I'he oil may be heated in the heating' coil 33 to a temperature of from about. Y 500 F. to about 650 F., for example. vTheheated oil may be delivered into a fractionating towel` 38 by means of a pipe 39.

Contacting devices such as the baiiies 4I 'may'. be Iprovided in the tower 38. Reiiux liquid, which may consist of low boiling petroleum oil, `may be introduced into the tower 38 thru a pipe 42. A

, valve 33, which is situated in the pipe A2, regulatesr the amount .of reflux liquid which is de-rvr 30i livered into the fractionating tower 38. f

In the fractionatingtower 38 substantially all of the low boiling petroleum oil contained in the oil mixture which is introduced linto the tower 3B thru the pipe 39 may be vaporized and separated 35;

from the heavier oil which is associatedv therewith. Said heavier oil contains the lubricating oil which it is an objectfof this invention to recover. 'I'he low boiling petroleum oil vapors may be withdrawn from the tower 38 thru a pipe Ml. 1340 The low boiling petroleum oil vapors. whichY are withdrawn from the tower 38, together with'va- I porized reflux liquid, 4may be. delivered into a fractionating tower 46. '-The'fractionating towers I3, 38 and 46 preferablyare maintained uri-45 der substantially atmospheric pressure. Contacting devices such as the baiiiesdl may be provided in the tower 46. .Reflux low boiling-which may consist of light petroleum oil, may be introduced into the tower 46 thrufa pipe 48. Theta() pipes 42 and 48 are supplied with reiiux liquid by a common supply pipe 49. A valve 50, which is situated in the pipe 48, regulates the amount of reflux liquid which is delivered into-.the fractionating tower 46. 5.55

In the fractionating tower 4S substantiallyr all of the low boiling petroleum oil vapors withdrawn from the tower 38 may becondensed. Uncon- ,densed gases may be withdrawn from the tower 46 thrua pipe 5I. These gases preferably-'are i60 `treated to remove objectionabley compounds therefrom before discharging them to the atmosphere.

The low boiling petroleum oil which is condensed in the tower 4S may be-.withdrawn'from the tower it thru a pipe53; A valve 53,-which is situated in the pipe 53, regulatesthe amount-of low boiling petroleum oil .whichv isv withdrawn from the tower ..46. A part of the low boiling petroleum oil withdrawn from the tower l136 may f7.0

be delivered to a heating coil 54 by means of a pump 55. The heating coil-#54 is situated ina furnace 56. A burner 51 isprovided Vforisupply-` ing heat to the heating coil 5.4. A valve #158,

which is situatedin the -.pipe'f53, regulates Athe '(5.7

' drum 65.

amount of low boiling petroleumv oil which is delivered to .the heating coil 54. 1 I The low boiling petroleum oil may be heated in the heating coil 54 to a temperature of from about 700 F. yto about 900 F., for example, and delivered into the tower I3 thru the pipe I6. The low boiling petroleum oil enters the tower I3 as a vapor and is used to heat the acid oil which is delivered into the tower I3 thru the pipe I0.

Said low boiling petroleum oil preferably is of a type that is not' easily decomposed upon heating; VIt'isfnot maintained at high temperatures for suflcient time to effect an appreciable amount of cracking .or decomposition thereof.

Apart ofthe low boiling petroleum oil withdrawn from the tower 46 may be diverted from the pipe'53, thru a by-pass pipe 60, and passed thru a cooling coil 6I which is situated in a water'box 62. A valve 64, which is situated in the by-pass Y' pipe 60, regulates the amount of low boiling petroleum oil which is passed thru the cooling coilv 6|.

The low boiling petroleum oil leaving the cooling coil 6| maybe delivered into an accumulator It may be withdrawn from the accumulator drum 65 thruthe pipe 40, by means of a pump 68. Partof the low boiling petroleum oil withdrawn from the accumulator drum 65 may be delivered by the pipe 40, thru the branch' pipes 42 and 48, to towers 38 and 46, respectively, to be used as reflux therein. The remainder may be discharged from the system thru a branch pipe 61. A valve 68 in the branch pipe 61 regulates the amount of low boiling petroleum oil which is discharged from the system. Ihe ylow boiling petroleum `oilwhich is discharged from the system may be used again in the process, for separating a fresh supply Vof acid sludge.

A relatively heavy oil may be withdrawn from the tower 38 thru a pipe 69. This oil contains the lubricating oil which it is an object of this invention to recover. A valve 10, which is situated in the pipe 69, regulates the amount of said heavy oil which is withdrawn fromthe tower 38.

The heavy oil withdrawn from the tower 38 may be delivered to a heating coil 1I by means of a pump 12. The heating coil `1l is situated in afurnace 14. A burner 15 is provided for supplying heat to the heating coil 1|. The heavy oil may be heated in the heating coill1| to a temperature of from about 650 F. to'about 800 F. and delivered yinto a fractionating tower 16 thru a pipe 11. An alkali such as sodium hydroxide may be introduced into the heated oil which is moved thru the pipe 11 by means of a branch pipe 10 which is connected to the pipe 11. A valve 80, which is situated in the pipe10, regulates the amount of alkali which is delivered into the pipe 11.

A pressure less'than atmospheric preferably is maintained in the fractionating tower 16. Steam may be introduced into the tower 16 thru a pipe 8|.4 A valve 8?., which is situated in the pipe 8|, regulates the amount of steam which is delivered to the tower 16.

Contact devices such as the 'bailles 83 may be provided in the tower 16. Reflux liquid, which may consist of water, may be delivered to the tower 16 thru a pipe 84. A valve 85, which is situated in the pipe 84, regulates the amount of reflux liquid which is delivered to the tower 16.

Trap trays 86 and 81 are provided in the fractionating tower 16 for collecting and withdrawing distillate lubricating oils which may be separated from the heated oil. Said distillatelubricating oils may be withdrawn from the trap trays 86 and 81 thru pipes 88 and 89, by means of pumps 90 and 9|, respectively, which are situated insaid pipes. The distillate lubricating oils withdrawn from the trap trays 86 and `81 maybe passed thru cooling coils92 and 93, which are situated infwater boxes 94 and 95, and discharged from the'system.

The heavy oil withdrawn from the tower 38 may contain emulsifying constituents, including certain organic'acids, which are undesirable in a finished 4lubricating oil. These vcompounds may be converted into soaps by causing them to react with the alkali which is introduced into the pipe 11; The resulting'organic acid soaps may be separated by distillation in the tower 16 to produce distillate lubricating oils which are substantilly free of emulsifying constituents. The organic acid soaps may be separated from the residual oil by extraction with a liquefied normally gaseous hydrocarbon such as propane.

' The distillate lubricating oils which are withdrawn from the tower 16 may be further refined, for example, by treatment with a solvent such as furfural, treatment with sulfuric acid, neutralizing and decolorizing by treatment with adsorbent clay, and dewaxing;

A residual lubricating oil `may be withdrawn from lthe tower 16 thrua'pipe 96, by means of a pump S1. A valve 88, which is situated in the pipe 06, regulates the amount of residual oil l which is `withdrawn from-the tower i6. The

residual lubricating oil withdrawn `from the: tower 16 may be passed thru a cooling coil 90,

which is situated in a water box |00, and dis charged from the system.

The residual lubricating oil which is withdrawn from the tower 18 may be further refined by treatmenty with a liqueed normally gaseous hydrocarbon such as propane, to separate therefrom contained asphaltic compounds and organic l acid soaps. It may then be rened, for example, by treatment with sulfuric acid, neutralizing and boiling petroleum oil, together with vaporized re.

flux liquid, maybe withdrawn from the tower 16 as a vapor, thru a pipe- I 0I. The low boiling petroleum oil vapors withdrawn from the tower16 may be condensed by passing them thru a heat exchanger |03 in which they are cooled by indirect contact with a cooling liuid which is delivered to the heat exchanger |03 by a pipe |08 and withdrawn therefrom thru a pipe |05. The condensed vapors may be withdrawn from the heat exchanger |03, thru a pipe |01 and delivered into fractionating tower |08. Reflux liquid, which may consist of water, may be delivered into the tower |08 thru a pipe I I0. A valve HI, which is edoy situated in the pipe H0, regulates the amount of reux liquid which is delivered into the fractionating tower |08. ,Contact` devices such as the baffles ||2 may be provided in the fractionating tower |08. The condensed low boiling petroleum oil may be withdrawn from Athe fractionating tower |08 thru a pipe ll3, by means of a pump H4. A valve II5, which is situated in the pipe H3, regulates the amount of low boiling petroil;4

iux liquid, may be withdrawn from the fractionating tower |08 thru a pipe H6. Said uncon- 1 densed gases and vaporized reux liquid are delivered to a barometric condenser H8. Water maybe delivered to the barometric condenser H8 thru a pipe H9. A valve |28, which is situated in the pipe H9, regulates the amount of Water which is delivered to the barometric condenser I i8. Aportion of said gases and'vaporized reux liquid may be condensed by the barometric condenser and Withdrawn thru theftail vpipe |23.` The gases which are not condensedby the barometric condenser H3 may be withdrawn by a Vacuum pump I2! which is provided for the purpose of maintaining a partial vacuum in the fractionating towers I6 and 108.

lObviously `many modications -and variations of the invention as hereinbefore set forth may be made Without departing from the spirit and scopel thereof and only such limitations should be imposed as are indicated in the appended claims.

I claim: v

1. The method of recovering lubricating oil from acid sludge derived from the treatment of petroleum lubricating oil with sulfuric acid which comprises adding lovvl boiling petroleum oil and water vto the acid sludge, separating from the sludge an acid oil consisting of a portion of the sludge dissolved in the 10W boiling petroleum oil, an asphaltic material which is relatively insoluble in the low boiling petroleum oil, and weak acid neutralizing the acid oil by heatingit to decompose and vaporize contained acid compounds, separating the acid vapors, distilling the neutralized oil and separating therefrom `the loW boiling petroleum oil, and recovering lubricating oil from the oil remainingvafter the `separation` of the low boiling petroleum oil.

2. The method of recovering lubricating oil froml acid sludge derived from the treatment of petroleum lubricating oil with sulfuric acid which y comprises adding low boiling petroleum oil and Water to the acid sludge, separating from the sludge an acid oil consisting of a portion of the sludge dissolved in the low boiling petroleum oil,

an asphaltic material which is relatively insoluble in the loW boiling petroleiun oil, and weakacd, neutralizing the acid oil by heating it to decompose and vaporize contained acid compounds, separating the acid vapors, distilling the neutralized oil and separating `therefrom the `lovv boiling petroleum oil and a distillate lubricating oil. v

3. The' method of recovering lubricating oil from-'acid sludge derived from the treatment of petroleum lubricating oil with sulfuric acid which ad.; comprises adding low boiling petroleum oil and Water to the acid sludge, separating from the sludge an acid oil consisting of a portion of the*` y l sludge dissolved in the low boiling petroleum oil,

an asphaltic material Whichis relatively insoluble` in the" 10WY boiling 4'petroleum oil, 'and weak acid, neutralizing the' acid oil by heating ittodecompose and vaporize containedv acid compounds, separating the acid vapors, distilling the neutral.; ized oil and separating therefrom constituents of low boiling point, and recovering lubricating oil from the oil-,remaining after the separation-of the low boiling point consituents.

4. The VmethodV of recovering lubricating oil fromiacid sludge derived from the treatment of petroleum lubricating oil with sulfuric acid which' comprises adding low boilingpetroleumioil and Water to the acid sludge, separating from the sludge an acid oil consisting of a portion of thesludge dissolved in the low boiling petroleum oil, an asphaltic material which is relatively insoluble in the low boiling petroleum oil, andiweak acid, neutralizing the acid'oil by heating it to decompose and vaporize contained acid come pounds, separating the acid vapors, distilling the neutralized oil under substantially atmospheric' pressure and separating therefromjthe low boil-A ing petroleum oil, distilling the remaining oil under less'than atmospheric pressure and separat-` ing therefrom a distillate lubricating oi1.`

5. The method Yof vrecoveringlubricating oil from acid sludgederived from` the treatmentoiv petroleum lubricating oil With sulfuric acidwhich comprises adding low boiling petroleumzoil` and water to the acid sludge, separating from the sludge an acid oil consisting of a portion of the e sludge dissolved kin the 10W-boiling petroleumoil, an asphaltic material which is relatively insolubley in the 10W boiling petroleum oil, and Weak acid, neutralizing the acid oil by heating it to decompose .and vaporize containedacid compounds, separating the acidvapors, distilling thel neutralized oil under substantially atmospheric pressure-:and separating. vtherefrom the low boiling petroleum oil, -distilling the remaining oil under less than atmospheric pressure and. in the presence Vof `an alkali, and `separating therefrom a distillate lubricating oil which is substantially free of emulsifying constituents:

6. The method of recovering l lubricating oil from acid sludge derived from `the treatment rof petroleum lubricating oil with sulfuric acid Whichcomprisesaddinglovvv boiling petroleum oil and.

Waterto the vacid sludge, separating from the sludge anacidv oil consisting of a portion of thesludge `dissolved in thelow boiling petroleum oil, an asphaltic material which is relatively insoluble inthe low boiling petroleum oiland-weak acid,

neutralizing the acidvr oil by heating .it to decom constituents, of low boiling? point, and recoveringV lubricatingvfoil from the oil remaining after the separation of the lowboiling point constituents. l JUDSON BRUCEV SYN'NO'II'I, JR.

lilil 

